Dataset Information

Antibodies to antigenic site A of influenza H7 hemagglutinin provide protection against H7N9 challenge.

ABSTRACT: Identifying major antigenic and protective epitopes of the H7 hemagglutinin (HA) will be important for understanding the antibody response to vaccines developed against the novel influenza H7N9 viruses that emerged in China in 2013. To facilitate antigenic characterization of the H7N9 HA and to develop reagents for evaluation of H7N9 candidate vaccines, we generated a panel of murine monoclonal antibodies (mAbs) to the HA of A/Shanghai/2/2013 using mammalian cell-derived virus-like particles (VLP) containing the H7 HA. Neutralizing antibodies identified an HA epitope corresponding to antigenic site A on the structurally similar influenza H3 hemagglutinin. Importantly, the neutralizing antibodies protect against A/Shanghai/2/2013 challenge. This antigenic site is conserved among many H7 viruses, including strains of both Eurasian and North American lineage, and the isolated neutralizing antibodies are cross-reactive with older H7 vaccine strains. The results indicate that the identified antigenic site is a potentially important protective epitope and suggest the potential benefit of cross-reactive antibody responses to vaccination with H7 candidate vaccines.

SUBMITTER: Schmeisser F

PROVIDER: S-EPMC4309539 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Antibodies to antigenic site A of influenza H7 hemagglutinin provide protection against H7N9 challenge.

Schmeisser Falko F Vasudevan Anupama A Verma Swati S Wang Wei W Alvarado Esmeralda E Weiss Carol C Atukorale Vajini V Meseda Clement C Weir Jerry P JP

PloS one 20150128 1

Identifying major antigenic and protective epitopes of the H7 hemagglutinin (HA) will be important for understanding the antibody response to vaccines developed against the novel influenza H7N9 viruses that emerged in China in 2013. To facilitate antigenic characterization of the H7N9 HA and to develop reagents for evaluation of H7N9 candidate vaccines, we generated a panel of murine monoclonal antibodies (mAbs) to the HA of A/Shanghai/2/2013 using mammalian cell-derived virus-like particles (VL ...[more]

PMID: 25629172

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Project description:UNLABELLED:The emergence of avian H7N9 viruses in humans in China has renewed concerns about influenza pandemics emerging from Asia. Vaccines are still the best countermeasure against emerging influenza virus infections, but the process from the identification of vaccine seed strains to the distribution of the final product can take several months. In the case of the 2009 H1N1 pandemic, a vaccine was not available before the first pandemic wave hit and therefore came too late to reduce influenza morbidity. H7 vaccines based on divergent isolates of the Eurasian and North American lineages have been tested in clinical trials, and seed strains and reagents are already available and can potentially be used initially to curtail influenza-induced disease until a more appropriately matched H7N9 vaccine is ready. In a challenge experiment in the mouse model, we assessed the efficacy of both inactivated virus and recombinant hemagglutinin vaccines made from seed strains that are divergent from H7N9 from each of the two major H7 lineages. Furthermore, we analyzed the cross-reactive responses of sera from human subjects vaccinated with heterologous North American and Eurasian lineage H7 vaccines to H7N9. Vaccinations with inactivated virus and recombinant hemagglutinin protein preparations from both lineages raised hemagglutination-inhibiting antibodies against H7N9 viruses and protected mice from stringent viral challenges. Similar cross-reactivity was observed in sera of human subjects from a clinical trial with a divergent H7 vaccine. Existing H7 vaccine candidates based on divergent strains could be used as a first line of defense against an H7N9 pandemic. In addition, this also suggests that H7N9 vaccines that are currently under development might be stockpiled and used for divergent avian H7 strains that emerge in the future. IMPORTANCE:Sporadic human infections with H7N9 viruses started being reported in China in the early spring of 2013. Despite a significant drop in the number of infections during the summer months of 2013, an increased number of cases has already been reported for the 2013-2014 winter season. The high case fatality rate, the ability to bind to receptors in the human upper respiratory tract in combination with several family clusters, and the emergence of neuraminidase inhibitor-resistant variants that show no loss of pathogenicity and the ability to transmit in animal models have raised concerns about a potential pandemic and have spurred efforts to produce vaccine candidates. Here we show that antigen preparations from divergent H7 strains are able to induce protective immunity against H7N9 infection.

Project description:Avian A/H7 influenza viruses are a global threat to animal and human health. These viruses continue to cause outbreaks in poultry and have caused the highest number of reported zoonotic infections to date, highlighting their pandemic threat. Evidence for antigenic diversification of avian A/H7 influenza viruses exists; however, knowledge of the drivers and molecular basis of antigenic evolution of these viruses is limited. Here, antigenic cartography was used to analyze the global antigenic diversity of A/H7 influenza viruses and to determine the molecular basis of antigenic change in A/H7N9 viruses. A phylogenetic tree based on all available A/H7 HA sequences was generated, from which 52 representative, genetically diverse, antigens were selected for antigenic characterization using hemagglutination inhibition assays. The resulting data were used to compute an antigenic map using multidimensional scaling algorithms. High antigenic relatedness was observed between antigens and sera belonging to genetically divergent A/H7 (sub)lineages. The most striking antigenic change relative to the timespan of virus isolation was observed for the A/H7N9 viruses isolated between 2013 and 2019 in China. Amino acid changes at positions 116, 118, 125, 130, 151, and 217 in the hemagglutinin globular head were found to be the main determinants of antigenic evolution between A/H7N9 influenza virus prototypes. The A/H7 antigenic map and knowledge of the molecular determinants of their antigenic evolution will aid pandemic preparedness against A/H7 influenza viruses, specifically regarding the design of novel vaccines and vaccination strategies. IMPORTANCE A/H7 avian influenza viruses cause outbreaks in poultry globally, resulting in outbreaks with significant socio-economical impact and zoonotic risks. Occasionally, poultry vaccination programs have been implemented to reduce the burden of these viruses, which might result in an increased immune pressure accelerating antigenic evolution. In fact, evidence for antigenic diversification of A/H7 influenza viruses exists, posing challenges to pandemic preparedness and the design of vaccination strategies efficacious against drifted variants. Here, we performed a comprehensive analysis of the global antigenic diversity of A/H7 influenza viruses and identified the main substitutions in the hemagglutinin responsible for antigenic evolution in A/H7N9 viruses isolated between 2013 and 2019. The A/H7 antigenic map and knowledge of the molecular determinants of their antigenic evolution add value to A/H7 influenza virus surveillance programs, the design of vaccines and vaccination strategies, and pandemic preparedness.

Project description:Since 2013, H7N9 avian influenza viruses (AIVs) have caused more than 1,500 human infections and the culling of millions of poultry. Despite large-scale poultry vaccination, H7N9 AIVs continue to circulate among poultry in China and pose a threat to human health. Previously, we isolated and generated four monoclonal antibodies (mAbs) derived from humans naturally infected with H7N9 AIV. Here, we investigated the hemagglutinin (HA) epitopes of H7N9 AIV targeted by these mAbs (L3A-44, K9B-122, L4A-14, and L4B-18) using immune escape studies. Our results revealed four key antigenic epitopes at HA amino acid positions 125, 133, 149, and 217. The mutant H7N9 viruses representing escape mutations containing an alanine-to-threonine substitution at residue 125 (A125T), a glycine-to-glutamic acid substitution at residue 133 (G133E), an asparagine-to-aspartic acid substitution at residue 149 (N149D), or a leucine-to-glutamine substitution at residue 217 (L217Q) showed reduced or completely abolished cross-reactivity with the mAbs, as measured by a hemagglutination inhibition (HI) assay. We further assessed the potential risk of these mutants to humans should they emerge following mAb treatment by measuring the impact of these HA mutations on virus fitness and evasion of host adaptive immunity. Here, we showed that the L4A-14 mAb had broad neutralizing capabilities, and its escape mutant N149D had reduced viral stability and human receptor binding and could be neutralized by both postinfection and antigen-induced sera. Therefore, the L4A-14 mAb could be a therapeutic candidate for H7N9 AIV infection in humans and warrants further investigation for therapeutic applications. IMPORTANCE Avian influenza virus (AIV) H7N9 continues to circulate and evolve in birds, posing a credible threat to humans. Antiviral drugs have proven useful for the treatment of severe influenza infections in humans; however, concerns have been raised as antiviral-resistant mutants have emerged. Monoclonal antibodies (mAbs) have been studied for both prophylactic and therapeutic applications in infectious disease control and have demonstrated great potential. For example, mAb treatment has significantly reduced the risk of people developing severe disease with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In addition to the protection efficiency, we should also consider the potential risk of the escape mutants generated by mAb treatment to public health by assessing their viral fitness and potential to compromise host adaptive immunity. Considering these parameters, we assessed four human mAbs derived from humans naturally infected with H7N9 AIV and showed that the mAb L4A-14 displayed potential as a therapeutic candidate.

Dataset Information

Antibodies to antigenic site A of influenza H7 hemagglutinin provide protection against H7N9 challenge.

Publications

Antibodies to antigenic site A of influenza H7 hemagglutinin provide protection against H7N9 challenge.

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